N-(alpha, alpha, alpha-trichloroacetyl)carbamates



United States Patent No. 455,586 4 Claims. (Cl. 260-482) Thisapplication is a division of copending application Ser. No. 221,301,filed Sept. 4, 1962, and now US. Patent 3,213,135.

This invention relates to a novel process whereby new and usefulchloroacetyl isocyanates of the formula wherein n is a whole number from1 to 3 are made.

The chloroacetyl isocyanates of this invention are prepared by heatingunder anhydrous conditions to effect evolution of hydrogen chloride amixture of one mole of a chloroacetamide of the formula ClnCH3-n-fi-NH2wherein n is a whole number from 1 to 3 and at least one mole of oxalylchloride in the presence of an inert organic liquid, and thereafterdistilling from the reaction mass said chloroacetyl isocyanate.

A wide range of reaction conditions can be employed in preparing thesechloroacetyl isocyanates provided the reaction conditions result in theevolution of hydrogen chloride which is a by-product of the reaction. Ingeneral it is preferable to reflux the reaction mixture and Whilerefluxing to remove the hydrogen chloride as it forms. Refluxingtemperatures in the range of from about 35 C. to about 100' C. have beenfound highly desirable. With respect to pressure either pressures aboveor below atmospheric pressure can be employed, however in general it issatisfactory to employ atmospheric pressure.

Although theoretically the amide reactant and oxalyl chloride combine inequimolecular amounts to produce the desired isocyanate it isadvantageous to employ an excess of oxalyl chloride, for example up toabout two moles per mole of amide.

The inert organic liquid employed in the process of this invention willbe a liquid alkane or a liquid chlorine substituted alkane or mixturesthereof, e.g., n-pentane, n-hexane, Z-methylpentane, 3-methylpentane,n-heptane, Q-methylhexane, dichloromethane, 1,1-dichloroethane, 1,Z-dichloroethane, chloroform, carbon tetrachloride, isobutyl chloride,and mixtures thereof. In general it is preferable that the amount ofsaid inert organic liquid present throughout the course of the reactionbe that at least suflicient to maintain the chloroacetyl isocyanateproduced in solution.

The chloroacetyl isocyanates prepared in accordance with the process ofthis invention include ot-chloroacetyl isocyanate, u,a-dichloroacetylisocyanate and oc,oc,ot-'t1ichloroacetyl isocyanate. These materials arereadily hydrolyzed and therefore when stored should be kept free ofmoisture, as for example stored under refrigerative conditions either assuch or dissolved in an anhydrous inert solvent.

These chloroacetyl isocyanates react with a variety of compounds toprovide a large number of useful compounds. For example the reacting ofequimolecular proportions of the chloroacetyl isocyanate (1) And analiphatic alcohol or aliphatic mercaptan of the formula RXH wherein X'issulfur or oxygen and 3,318,947 Patented May 9, 1967 wherein R is a Caliphatic hydrocarbyl radical (e.g., methyl, ethyl, isopropyl, amyl,allyl, butenyl, propynyl, etc.) or a chlorine substituted C aliphatichydrocarbyl radical (e.g., Z-chloroethyl, 2,3-dichloropropyl,2-chloroallyl, 3-ohlo-robut-2-enyil, etc. )provides esters of theformula which esters are useful as herbicides, e.g., at an applicationrate of 25 pounds per acre methyl-N-(a,a,a-trichloroacetyl)carbamate(M.P. 10'51=06- C.) exhibited excellent preemergent control of suchnarrow leaf plants as brome grass, rye grass, foxtail, crab grass andsorghum. Other useful esters so obtainable from the appropriate alcoholor mercaptan include isopropyl N-(a-chloroacetyl) carbamate (M.P.lOl-l02 C.), methyl N-(a,u-dichloroacety1)thiocarbamate, 2-chloroallylN-(0t,0t,0c-tll0l'1l0l0- acetyDcarbamate, etc.

(2) And a substituted phenol or thiophenol such as the variouschlorophenols, chlorothiophenols and nitrophenols provides esters of theformula wherein X is sulfur or oxygen and wherein R is a phenyl radicalhaving one or more chloro and/or nitro substituents which esters areuseful as herbicides, e.g., at an application rate of 25 pounds per acre4-chlorophenyl N-(a,u,o-trichloroacetyl)carbamate (M.P. 157 C.)exhibited excellent contact herbicidal control of narrow leaf and broadleaf plants.

(3) And a primary or secondary amine of the formula ANHB wherein A ishydrogen or a C aliphatic radical (e.g., methyl, ethyl, isopropyl,arnyl, allyl, propynyl, 2-chloroethyl, Z-chloroallyl, etc.) or a phenylradical or an alkyl substituted phenyl radical or chlorine substitutedphenyl radical and wherein B is a C aliphatic radical (e.g., methyl,ethyl, isopropyl, amyl, allyl, propynyl, 2-chloroethyl, 2-chloroally1,etc.) or a phenyl radical or an alkyl substituted phenyl radical or achlorine substituted phenyl radical provides substituted ureas of theformula acetyl)-N-isopropyl-N-phenyl urea, N-(a-chloroacetyD-N',N'-dimethyl urea (M.P. 82-85" C.), etc.

As illustrative of the method of manufacture of the chloroacetylisocyanates of this invention and the preparation of useful derivativesthereof is the following:

Example I To a suitable reaction vessel equipped with a thermometer,agitator and reflux condenser is charged at room temperature 12.8 partsby weight of a,ot-dichloroacetamide, 13.0 parts by weight of oxalylchloride and 88.2 parts by weight of 1,2-dichloroethane. The so-chargedmass is then heated to reflux while agitating then refluxed (about 83C.) for four hours. Thereafter the resulting 3 mass is subjected tovacuum distillation and the cut (10.45 parts by weight) taken at 135 C.at 35 mm. of mercury is a,a-dich=loroacetyl isocyanate, n is 1.4600.

Example la To a suitable reaction vessel is charged 3.1 parts by Weightof a,a-dichloroacetyl isocyanate dissolved in 25 parts by weight ofdichloromethane. While maintaining the temperature at about C. and withagitation there is added 3.2 parts by Weight of 3,4-dichloroanilinedissolved in 25 parts by weight of dichloromethane. The solution is thenconcentrated by boiling oil the excess dichloromethane. To the soconcentrated solution is added suflicient hexane to precipitate thedissolved solids. The precipitate is filtered oil and dried. The driedproduct (5.8 parts by weight) is N-(a,u-dichl0roacetyl)N'-(3,4-dichlorophenyl) urea which after recrystallization is found to melt at157-159 C.

Analysis.Theory, 8.86% N, 44.88% Cl. 8.90% N, 45.25% Cl.

Example 1b Found,

Employing the procedure of Example Ia but replacing 3,4-dichloroanilinewith an equimolecular amount of dimethy lamine there is obtainedN-(a,a-dichloroacetyl)-N, N-dimethylurea.

Example II To a suitable reaction vessel equipped with a thermometer,agitator and reflux condenser is charged at room temperature 16.2 partsby Weight of a,a,a-trichloroacetamide, 101 parts by weight of1,2-dichloroethane, and 12.7 parts by weight of oxalyl chloride. Withagitation the so-charged mass is heated to reflux and refluxed (about 80C.) for twenty-four hours. Thereafter the resulting mass is subjected tovacuum distillation and the cut (11.3 parts by weight) taken at 80-85 C.at 20 mm. of mercury is a,a,a-trichloroacetyl isocyanate, 11 is 1.4755.

Example Ila To a suitable reaction vessel is charged 3.8 parts by weightof a,a,a-trichloroacety l isocyanate dissolved in 25 parts by weight ofdichloromethane. While maintaining the temperature at about 0 C. andwith agitation is added 3.2 parts by weight of 3,4-dichloroanilinedissolved in 25 parts by weight of dichloromethane. The solution is thenconcentrated by boiling off the excess dichloromethane. To the soconcentrated solution is added suflicient hexane to precipitate thedissolved solids. The precipitate is filtered off and dried. The driedproduct (5.6 part-s by weight) isN-(a,a,a-trichloroacetyl)-N-(3,4-dichlorophenyl) urea which afterrecrystallization is found to melt at 175 C.

Analysis.Theory, 8.00% N, 50.59% Cl. 8.11% N, 50.68% Cl.

Example Ilb To a suitable reaction vessel is charged 50 parts by weightof anhydrous methanol. While maintaining the temperature at about 0 C.and with agitation is added dropwise 3.8 parts by weight of colda,oc,a-trichloroacetyl isocyanate. The mass is evaporated to dryness invacuo and the residue recrystallized from a dichloromethanehexanemixture and dried. The dried product (44 parts by weight) is methylN-(a,a,a-trichloroacetyl)carbamate Which material melts at 105106 C.

Example 111 To a suitable reaction vessel equipped with a thermometer,agitator and reflux condenser is charged 56.1 parts by weight ofa-chloroacetamide, 81 parts by weight of oxalyl chloride and 88.2 pantsby weight of 1,2-dichloroethane. With agitation the so-charged mass isheated to reflux and refluxed (about 83 C.) for two hours. Thereafterthe reaction mass is subjected to vacuum distillation and the cut (46.0parts by weight) taken at 50-55 C. at 20 mm. is a-chloroacetylisocyanate, n is 1.4580.

Found,

4 Example 11111 To a suitable reaction vessel is charged 2.4 parts byweight of a-chloroacetyl isocyanate dissolved in 25 parts by weight ofdichloromethane. While maintaining the temperature at about 0 C. andwith agitation there is added 3.2 parts by weight of 3,4-dichloroanilinedissolved in 25 parts by weight of dichloromethane. The solution is thenconcentrated by boiling ofl? the excess dichloromethane. To the soconcentrated solution is added suflicient hexane to precipitate thedissolved solids. The precipitate is filtered ofr' and dried. The driedproduct (4.5 parts by weight) isN-(a-chloroacetyl)-N'-(3,4-dichlorophenyl) urea which afterrecrystallization is found to melt at .160 C. Analysis.Theory, 9.95% N,37.78% Cl. Found, 9.94% N, 37.72% Cl.

Example 11117 To a suitable reaction vessel is charged 2.4 parts byweight of a-chloroacetyl isocyanate dissolved in 25 parts by weight ofcold dichloromethane. While agitating 2.6 parts by weight of4-chlorophenol is added. The solution is concentrated by boiling off theexcess dichloromethane. To the so concentrated solution is addedsuflicient hexane to precipitate the dissolved solids. The precipitateis filtered off and dried to give 3.6 parts by weight of 4- chlorophenylN-(a-chloroacetyl)carbamate which after recrystallization is found tohave a melting point of 147-149" C.

Example IIIc Employing the procedure of Example IIIb but replacinga-chloroacetyl isocyanate with an equimolecular amount ofa,a,a-trichloroacetyl isocyanate there is obtained 4-chlorophenylN-(a,a,a-trichloroacetyl) carbamate, M.P. 155-157 C.

Example IHd Employing the procedure of Example IIIb but replacing4-chlorophenol with an equimolecular amount of 4-ch1orothiophenol thereis obtained as a white solid 4-chlorophenylN-(a-chloroacetyl)thiolocarbamate.

Example IIIe Employing the procedure of Example IIIa but replacing3,4-dichloroaniline with an equimolecular amount of methyl mercaptanthere is obtained methyl N-(a-chloroacetyl)thiolocarbamate, M.P. 1341 35C.

The terminus of the reaction is readily determined by observing thecessation of evolution of hydrogen chloride. In the reaction stepbetween the amide and the oxalyl chloride it is desirable that the inertorganic liquid employed have a boiling point below that of the desiredisocyanate product. In instances wherein a precipitate forms either inthe reaction step or during the distillation operation or any timetherebetween it is usually desirable to add sufficient inert organicliquid of any of the aforedescribed types to dissolve the precipitatedsolids. In recovering the isocyanate product it is preferable to conductthe distillation operation under reduced pressure, e.g., at less than 50mm. of mercury, and which pressure permits a distillation temperature ofnot more than C.

While this invention has been described with respect to certainembodiments it is to be understood that it is not so limited and thatvariations and modifications thereof obvious to those skilled in the artcan be made without departing from the spirit or scope of thisinvention.

What is claimed is:

1. An N-(a,a,a-trichloroacetyl)carbamate of the formula 5 wherein X is achalkogen of atomic Weight less than 40, and wherein R is aliphoticcontaining from 1 to 5 carbon atoms and is selected from the groupconsisting of alkyl, alkenyl, alkenyl, chloroalkyl and chloroalkenyl.

2. An N-(a,a,a-trichloroacetyl)carbarnate of the formula llone-ii-mn-c-o-n 6 3. Methyl N-(a,u,a-trichloroacetyl)carbamate. 4.Isopropyl N (a,a,a-trichloroacetyl)carbamate.

References Cited by the Examiner FOREIGN PATENTS 202,721 1/ 1939Switzerland.

LORRAINE A. WEINB-ERGER, Primary Examiner. D. R. MAHANAND, ALBERT P.HALLUIM,

Assistant Examiners.

1. AN N-(A,A,A-TRICHLOROACETYL) CARBAMATE OF THE FORMULA